Cotesia Species
Braconid Wasps

There are many species in the Cotesia genus of parasitoid wasps.

Visit Pictures of many Braconidae species.

Adult females have an ovipositor that can penetrate the skin of early instar larvae. Often large numbers of tiny eggs are inserted under the larval skin, and emergent wasp larvae feed internally on the lymph and fatty tissues. At maturity, the wasp larvae eat their way out and spin elongate silken cocoons, attached to the back and sides of the caterpillar.

Cotesia electrae (Viereck, 1912), commonly known as the Electra Braconid Wasp, lives in many diverse habitats including grassland prairies, arid deserts, oak/pine forests, and riparian zones. This species attacks virtually all species of Agapema, Hemileuca, and Coloradia in western North America, especially in the southwestern United States.

Infected larvae feed and often develop to normal size with the wasp larvae making their exit when the host larvae appear mature. Unfortunately, parasitism is often very high among found larvae, and a collector can receive a nasty surprise after rearing found larvae to near maturity.

Hemileuca eglanterina larva and Cotesia species cocoons,
courtesy of Richard Wasson.

I think that the Cotesia cocoons that are depicted in the specimen above are probably those of Cotesia electrae which frequently attacks Hemileuca species.

Visit Richard Wasson's pictures and description of Cotesia on Hemileuca eglanterina.

Visit Kirby Wolfe's pictures and description of Cotesia electra on Hemileuca electra.

As far as I know it is virtually impossible to access whether found larvae have been infected by wasps of the Braconidae family until the wasp larvae/cocoons appear externally. Early instar larvae are the ones that are least likely to have been attacked, but these waps so attack even very samll larvae.

The Lepidotera larvae die during or after the parasitoid exit. As far as I know there is no cure or treatment.

Breeders who rear their own livestock in sleeves or cages, should check to make sure there are no breeches (holes, even small ones) in sleeves or cage coverings. These wasps are small and relentless.

I do not know the diapausing stage of Cotesia species, but I suspect the cocoons dislodge, fall to the ground, and the pupae inside the cocoons spend the colder months in diapause.

Use your browser "Back" button to return to the previous page.